Debt Instrument, Alternate Basis Spread on Variable Rate

No definition available.

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Namespace Prefix:	bxp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Extension Option (in months)

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Extension Option (in years)

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Number of extensions

+ References

No definition available.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
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Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

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Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Balance Type:	credit
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- Definition

The carrying amount as of the balance sheet date for the aggregate of other miscellaneous borrowings owed by the reporting entity.

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Balance Type:	credit
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- Definition

Amount of cash inflow from debt classified as other.

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Balance Type:	debit
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- Definition

The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with either short term or long term maturity that is uncollateralized (where debt is not backed by the pledge of collateral).

+ References

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- Definition

Amount of cash outflow for the payment of debt classified as other.

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- Definition

The cash outflow to repay long-term debt that is not secured by collateral. Excludes repayments of tax exempt unsecured debt.

+ References

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Period Type:

- Details

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Unsecured Term Loans (Details) $ in Thousands					9 Months Ended
Unsecured Term Loans (Details) $ in Thousands	Sep. 30, 2025 USD ($)	Apr. 22, 2025	Mar. 28, 2025 USD ($)	Sep. 27, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Apr. 08, 2025 USD ($)	Dec. 31, 2024 USD ($)	Jan. 04, 2023 USD ($)
Debt Instrument [Line Items]
Borrowings on unsecured term loans					$ 700,000	$ 0
Repayment of unsecured term loans					700,000	500,000
Repayments of Unsecured Debt					850,000	$ 700,000
Unsecured term loans, net	$ 796,798				$ 796,798			$ 798,813
Term Loan Facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.95%
2023 Unsecured Term Loan
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity									$ 1,200,000
Repayments of Unsecured Debt			$ 700,000
Term Loan Facility
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 700,000
Debt Instrument, Maturity Date			Mar. 30, 2029
Number of extensions			2
Extension Option (in months)			6
Proceeds from Unsecured Lines of Credit			$ 700,000
Debt Instrument, Basis Spread on Variable Rate		0.10%
Debt Instrument, Alternate Basis Spread on Variable Rate	0.00%				0.00%
Debt	$ 700,000				$ 700,000
2024 Unsecured Term Loan
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 100,000
Borrowings on unsecured term loans				$ 100,000
Number of extensions				3
Extension Option (in years)				1,000
Debt							$ 100,000